A "pandemic" of inactivity in poor areas of England is leading to premature deaths, a report has warned.

Thirteen of the top 15 local authorities where people are the most inactive also sit in some of the most deprived parts of the country, said experts from the not-for-profit health group, Ukactive.

Where inactivity levels are at their highest, early deaths also peak, their study found.

In the 15 most inactive local authorities, there is an average of 342 premature deaths per 100,000 people per year, compared with 242 in those where people exercise the most.

Councils, who took over responsibility for promoting exercise from the NHS last year, spent 2% of their annual public health budgets on programmes to boost activity last year, the report went on.

Some 5% have not allocated any cash to such programmes for 2013/14.

This is despite the fact inactivity costs the economy in each local authority £18 million per 100,000 people every year on average, the study found. Cutting physical inactivity by just 1% a year over a five-year period would save the UK economy just under £1.2 billion, it said.

Researchers found that the most inactive local authorities have, on average, a third fewer leisure facilities than the least inactive areas.

But they said there is no link between levels of exercise and the amount of green space in each region. This contrasts with a report published yesterday from the the Royal Institute of British Architects (RIBA), which found a lack of green space meant people were more likely to suffer ill health and walk less.

Overall, today's research said one in three people in the most deprived parts of England fail to raise their heartbeat for 30 minutes a month, even in separate 10-minute bursts.

David Stalker, chief executive officer of Ukactive, said inactivity was" a distinct risk to public health".

Fred Turok, chairman of Ukactive, said: "It's no longer acceptable that physical inactivity remains the forgotten cause of death in the UK. More deprived areas are faring worse in a physical inactivity pandemic - with no national strategy to improve our fitness levels, from before we take our first steps to our last."

Lord Sebastian Coe, who is backing the report, said: " Physical inactivity currently accounts for nearly one fifth of premature deaths in the UK. With projections showing that inactivity levels are due to increase by a further 15% by 2030, there is no doubt that the issue requires immediate national attention and urgent action."

Professor Kevin Fenton, national director for health and wellbeing at Public Health England (PHE), said: " PHE is committed to working with local and national partners to reduce levels of physical inactivity and the associated health, economic and social burden on local communities.

"Physical activity is undertaken across communities in a range of ways, from walking and cycling, through fitness, leisure and play to structured amateur and elite sport.

"We need to embrace and support this diversity through cross-sector collaboration and action to embed physical activity within daily life.

"Local government is at the centre of developing and leading a whole system approach across communities to reduce inactivity and encouraging more people to get more active, more often."

Ciaran Devane, chief executive of Macmillan Cancer Support, said: "Today's report exposes the stark reality of physical inactivity in England and the detrimental effect this is having on our health.